真核起始因子EIF3D通过内质网应激途径促进晚期肾癌舒尼替尼耐药的机制研究

Sunitinib is a first-line drug to treat advanced renal cell carcinoma(RCC). However, there is few effective treatment for advanced RCC with sunitinib resistance, the mechanism of which remains unclear. In the previous study, we found that the expression of eukaryotic translation initiation factor 3D (EIF3D) was significantly elevated in advanced RCC samples harvested from patients with sunitinib resistance. In RCC cell lines, we found that the EIF3D upregulated in a manner of sunitinib dose-dependent. In addition, expression of EIF3D in sunitinib resistance RCC cell lines was higher. Further studies showed that EIF3D may induce sunitinib resistance by promoting the activity of endoplasmic reticulum stress(ERS) pathway. This project is designed to explore the mechanism of EIF3D promotes the activity of ERS pathway and sunitinib resistance. Immunohistochemistry is applied to analyze the correlation among expression level of EIF3D, incidence of sunitinib resistance and prognosis of the RCC patients. Pdx animal models are used to test the role of EIF3D in regulating the ERS pathway and clarify the mechanisms and clinical significance of EIF3D in sunitinib resistance. This project may contribute to discover some potential molecular targets for treatment in RCC patients with sunitinib resistance, which may also build theoretical foundation for translational medicine.

舒尼替尼是治疗晚期肾癌的一线药物，舒尼替尼耐药严重制约了晚期肾癌的治疗效果，目前其机制仍不清楚。我们用基因芯片检测发现，真核起始因子EIF3D在晚期肾癌舒尼替尼耐药患者的转移灶中表达显著增高。用舒尼替尼处理肾癌细胞株可诱导EIF3D剂量依赖性地表达上调。在7Su3rd和ACSu3rd舒尼替尼耐药细胞株中，EIF3D的表达高于亲本株中的表达水平。进一步研究发现，EIF3D可能通过促进内质网应激(ERS)信号通路活性，诱导肾癌舒尼替尼耐药。本项目拟通过深入探索EIF3D促进ERS活性的具体机制，进一步解析肾癌舒尼替尼耐药机制。通过免疫组化等方法分析肾癌组织中EIF3D的表达水平与舒尼替尼耐药以及预后之间的相关性。通过Pdx动物模型验证EIF3D作为干预靶点的价值，阐明其在肾癌舒尼替尼耐药中的作用机制。本项目的实施有助于向临床治疗提供潜在的分子靶点，并为未来的转化医学应用奠定理论基础。

舒尼替尼是目前用于治疗肾细胞癌（RCC）的多靶点酪氨酸激酶抑制剂之一。但是，其临床疗效受到耐药的限制。我们前期研究发现，真核翻译起始因子3亚基D（EIF3D）是RCC发生和发展的致癌基因，本课题在既往的研究基础上，进一步研究表明：在具有获得性舒尼替尼耐药性的786-OR和ACHN-R细胞中，我们发现EIF3D表达高于舒尼替尼敏感的786-O和ACHN细胞。与舒尼替尼敏感性肿瘤组织相比，舒尼替尼耐药的肿瘤组织中的EIF3D水平也显著上调。功能研究表明，敲减EIF3D可降低舒尼替尼耐药株的细胞活力。机制研究表明，EIF3D与GRP78相互作用并通过阻断泛素介导的GRP78蛋白酶体降解来增强GRP78的蛋白质稳定性，进而使得GRP78的蛋白表达持续增加，并通过触发未折叠的蛋白应答激活内质网应激，从而诱导RCC细胞的舒尼替尼耐药，而沉默GRP78的表达则抑制了舒尼替尼耐药细胞的活力，进一步，过表达GRP78可以回复EIF3D沉默在体外和体内对舒尼替尼耐药株生长的抑制作用。综上所述，EIF3D在RCC细胞的舒尼替尼耐药中起着重要作用，这表明它可能是RCC舒尼替尼耐药的潜在治疗靶点，并为未来的转化医学应用奠定理论基础。